Joe, standing near a straight road, records the sound of the horn of a car trave

Question

Joe, standing near a straight road, records the sound of the horn of a car traveling at a constant speed. The recorded frequency as a function of the car's position along the road for trials at different car speeds is accurately graphed below.

A.)When the car is far away, the average of the frequencies moving in and out is ..... the frequency at rest.

The speed in trial S is ..... that in other trials.

The distance of Joe from the path in T is ..... in Q.
The speed in trial Q is ..... to that in T.
The speed in trial U is ..... that in other trials.
The speed in trial R is ..... that in U.
Choices are greater than, less than, or equal to.

b.)Using the data on the figure, calculate the speed of the car in trial S. Use 340 m/s for the speed of sound.

please help with both parts! thanks!

Explanation / Answer

Joe, standing near a straight road, records the sound of the horn of a car traveling at a constant speed. The recorded frequency as function of the car position along the road for trials at different car speeds is graphed.

http://www.flickr.com/photos/68377972@N03/6220825250/in/photostream

True, false, greater than, less than, equal to



A. The speed in trial E is ..... to that in B.

B. The lowest speed is in trial E.

C. The speed in trial D is ..... to that in A.

D. In trial A, Joe's distance from the path is ..... in D.

E. When the car is far away, the average of the frequencies moving in and out equals the frequency at rest.

F. The highest speed is in trial C.





A <
B T
C =
D: trial D, joe is very close to the track, from the steepness of the crossover.
>
E T
F T

"greater the velocity of the source, the lower the frequency heard" true for motion towards the listener, since the higher the velocity the greater the frequency shift. Misread this the first time, sorry.

"average frequencies equals the frequency at rest" true

D and A are traveling at the same speed, as you can see by the way they converge when the distances are long. The divergence closer in means joe is not as close to the track in A as in D

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